Generally, a pneumatic tubeless tire is made of a tread section with two side walls. Beads are located at the end of each side wall and are typically rigid. The beads fit onto a rim. Putting air pressure into the interior of the tire causes the beads to seat against the rim and securely hold the tire onto the rim. Air pressure is maintained because the bead presses a sealing surface on the tire against a sealing surface on the rim so as to preclude air loss.
Manufacturers have conceived various designs that will allow a pneumatic tubeless tire to continue to function after a loss of air pressure. One such design may be referred to as run-flat tire. The design and use of a run-flat tire is desirable for several reasons. First, a sudden loss of air pressure in a conventional tire can result in a shifting of the position of the tire, and subsequently, a change in the internal tensioning forces originally imparted by the tire on the rim to hold the tire thereon. The tire may become disengaged from the rim under certain circumstances.
Second, a loss of air pressure forces the crown of a conventional tire down onto the rim. The rim must then assume the loading from the weight of the vehicle and the dynamic forces of the ride. As the rim is not designed for this purpose, damage to either the rim or even the wheel and axle supporting the rim can result. This in turn can lead to costly repairs in addition to leaving the driver and passenger stranded.
An example of a design of a run-flat tire is illustrated in U.S. Pat. No. 5,891,279 that is owned by the assignee of the present invention and is incorporated by reference herein in its entirety for all purposes. Tire and rim assemblies of this type have a ring shaped insert, typically formed of a flexible elastomeric material, disposed on the rim. The tire surrounds this insert. When the tire loses air pressure, the tire will deform and contact the insert. The load of the vehicle and the dynamic forces of the ride will then be borne by the insert. The inserts allow drivers additional mileage by which to travel to a convenient location where the tire can be inspected and repaired or replaced.
Sometimes during operation of a run-flat tire that utilizes an insert, the insert could possibly slip or rotate in relation to the rim. Slipping of the insert is particularly possible during periods of high speed operation. The balance of the tire-insert-wheel assembly could be affected, resulting in vibration from the assembly during rotation. A method of testing the design of such inserts (also referred to as a support ring) on wheel assemblies is desired so that any slipping of the insert can be studied and reasonably reduced or eliminated where necessary and feasible.
Objects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned from practice of the invention.
In one exemplary embodiment, the present invention provides a method of testing a support ring used in a wheel assembly. This method includes positioning the support ring upon a wheel rim and noting the relative position of the support ring on the wheel rim. The wheel rim and support ring are then accelerated to a predetermined rotational speed. By predetermined rotational speed, it is meant only that a rotational speed for the test is selected. After reaching the predetermined rotational speed, the rotation of the wheel rim and support ring are brought to a stop at a controlled deceleration rate. The amount of any rotation of the support ring relative to the wheel rim is then determined.
In another exemplary embodiment of the present invention, a method of testing a run-flat tire component is provided that includes mounting the run-flat tire component on a wheel for testing. The position of the run-flat tire component relative to the wheel is marked. The wheel and the run-flat tire component are then rotated at a selected test speed. The wheel is decelerated at a determined rate of deceleration. The amount of rotation, if any, is then determined.
Another exemplary embodiment a method for centrifugally testing a run-flat tire component is provided that includes mounting a run-flat tire component on a wheel and connecting the wheel to a rotatable power source. A first mark is placed on the run-flat tire component and a second mark is placed on the wheel. The first mark and second mark are located adjacent to each other at the beginning of the test. The wheel is rotated at a determined speed and then slowed at a constant rate until the wheel stops rotating. A determination is then made as to whether the run-flat tire component has rotated relative to the wheel.
In further exemplary embodiments, a method for centrifugally testing a run-flat tire component includes the steps immediately discussed and further includes the step of recording the amount of any rotation of the run-flat tire component relative to the wheel. In yet another alternative embodiment, a method for centrifugally testing a run-flat tire component is provided that includes the steps immediately discussed and further includes the steps of increasing the determined speed by a selected increment and then repeating the steps of rotating, slowing, and determining. In still another exemplary embodiment, a method for centrifugally testing a run-flat tire component includes the steps discussed above and also includes the additional step of inspecting the run-flat tire component for damage after the step of slowing. Another embodiment of a method for centrifugally testing a run-flat tire component includes the steps discussed above, and further includes the steps of inspecting the run flat-tire component for damage after the step of slowing, increasing the determined speed by a selected increment, and repeating the steps of rotating, slowing, determining, and inspecting.
Another alternative embodiment of the present invention exists in providing a method for centrifugally testing a run-flat tire component that includes the steps discussed above and further includes the steps of inspecting the run-flat tire component for damage, increasing the determined speed by a selected increment, and repeating the steps of rotating, slowing, determining, and inspecting until a maximum determined speed is obtained. Another embodiment of a method for centrifugally testing a run-flat tire component includes the steps immediately discussed above and further includes the steps of inspecting the run-flat tire component for damage, increasing the determined speed by a selected increment, and repeating the steps of rotating, slowing, determining, and inspecting until rotation of the run-flat tire component relative to the wheel is determined. In still another embodiment, a method for centrifugally testing a run-flat tire component includes the steps immediately discussed above and further includes inspecting the run-flat tire component for damage, increasing the determined speed by a selected increment, and repeating the steps of rotating, slowing, determining, and inspecting until damage to the run-flat tire component occurs.
These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, are used to illustrate exemplary embodiments of the invention and, together with the description, serve to explain the principles of the invention. As will be apparent to one of ordinary skill in the art using the teachings disclosed herein, the present invention may be used in a variety of embodiments to test a variety of run-flat tire components.